Synthesis, Characterization and Electronic Structure of Dirhenadehyro[12]annulene Complexes.

Treatment of the SiMe3 -protected dichloro-rhenium carbyne complexes Re{≡CCH=C(R)C≡CSiMe3 }Cl2 (PMe2 Ph)3 (R = CMe3 , 1-adamantyl) with CsF in methanol directly afforded the 12-membered metallacycles {ReCl(PMe2 Ph)3 }2 {≡CCH=C(R)C≡C-}2 . The electronic structure of the metallacycle was investigated by density functional calculations. The UV-vis spectrum of the metallacycle shows a red-shifted band compared to that of the starting dichlorocarbyne complex. Treatment of {ReCl(PMe2 Ph)3 }2 {≡CCH=C(CMe3 )C≡C-}2 with HCl produced the dichloro-rhenium carbyne complex Re{≡CCH=C(CMe3 )C≡CH}Cl2 (PMe2 Ph)3 , which is consistent with the electronic structure of the 12-membered metallacycles.